One vertex per element, one color per generator, with an edge from x to x·s.
(2,6)(3,4)(7,8)(9,10)(11,15)(12,20)(13,16)(14,19)(17,22)(18,24)(21,23)(27,33)(28,35)(30,38)(32,36)(34,37)(39,40) involution — undirected(1,2)(3,6)(4,7)(5,8)(9,11)(10,14)(12,21)(13,18)(15,20)(16,23)(17,24)(19,22)(25,26,29,31)(27,30,34,39)(28,36,35,32)(33,40,37,38)(3,4)(6,7)(9,11)(10,15)(12,19)(13,18)(14,20)(16,24)(17,23)(21,22)(25,27)(26,30)(28,37)(29,34)(31,39)(32,40)(33,35)(36,38) involution — undirected(1,3,5,4)(2,7,8,6)(10,16)(11,18)(17,20)(19,21)(26,31)(30,39)(32,36)(38,40)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.